Lead (Pb) has been a major health hazard affecting the development of the CNS especially in young children. Understandably, numerous studies have been done to investigate its effects at the cellular and behavioral levels using both vertebrate and invertebrate models. My interest focuses on the cellular and neuro-toxicological aspects of Pb exposure using the bag cell neurons of the invertebrate mollusc, Aplysia. At the BioCurrents Research Center this summer, Pb-exposure (ranging from 0-200mM Pb) experiments were done and gross cellular morphology was assessed. The response was dose-dependent with higher Pb levels producing overt morphological changes. Within 30 min., the increased number of vacuoles along neurites and formation of jagged edges along as well as shrinking of neurites were observed. Whole cell neuronal staining was also done to detect Pb. The Mallory-Parker Staining method wherein a Pb-hematoxylin chelate is formed, gave some interesting results. Pb-exposed neurons showed differential staining in intensity within the soma. The nucleus had a denser uptake of stain which in turn was surrounded by a less intense reaction, and an even lighter but still definitive staining pattern along the soma perimeter. Work was also done using digital fluorescence microscopy to image the Ca2+ and determine what interaction(s) occurs in the presence of Pb. Bag cell neurons loaded with fura-2AM, a Ca2+ dye, were observed after Pb was infused into the medium. Preliminary results indicate a gradual increase of cytosolic Ca2+ within 5 min. of Pb infusion. Future work will include the use of the ion-selective probe to detect and changes in Ca2+ ion movements in the presence of Pb.